Telephone repeater system.



T. G. MARHN.

TELEPHONE REPEATER SYSTEM.

APPLICATION FILED APR. 16, 1910. RENEWED 111111 2, 1913.

Patented @1221), 1915.

s SEEE-TS-SHEBTI. 5 5

Ii/175M011? T- G. MARTIN.

TELEPHONE REPEATER SYSTEM.

APPLgcA'nou FILED APR. 16, mo. RgNEWED MAY 2, 1913.

3;, 1 36,9 1 2c Patented Apr. 20, 1915.

3 SHEETS-SHEET 2.

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IUUI @u T. G. MARTIN.

TELEPHONE REPEATER SYSTEM.

APPUCATION FILED APR.16,191D. RENEWED MAY 2,1913.

Patented Apr. 20, 1915.

3 SHBETSSHEET 3.

PZ/YTJVZESSES C q. a F

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W M m W W M w N w, M 1 M Au t E E SOIX chin

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it lple 112, 01* for th h pies re,

eyea ze ic SR 60 i the connect 111 trunk thrs a'm'mmnt on trunk princ 35 therefs mehi said reps 10 same 1- one 01' more, m zfir pose 0 ml? 1 sysiem.

awe ain that imp transmitter 23,

22, transmitter 23, induction coil 24, ringer 25, condenser 26 and impulse springs 27 and 28. The switch hook controls the substation circuits through the medium of the cam arm 29 and springs 30, 31 and 32. When the receiver is on the hook the arm 29 maintains spring 31 in contact with spring 32, thus bridging the ringer and condenser 26 in series across the line conductors 33' and 34. When the receiver is removed the hook is forced upward by a spring (not shown), allowing the spring 31 to disengage spring 32'and come into engagement with spring 30. By this action the circuit of the ringer 25 is opened and a bridge consisting of the rimary winding of induction coil 24, an impulse s rings 27 and 28 is closed across the line condhctors 33 and 34. The impulse wheel 22 carries upon its pe-' riphery the impulse teeth 35, and is secured to a shaft 36 to which there is also secured a dial (not shown) provided with .finger during this backward motion the spring 27 is forced out of engagement with the spring 28 to open the bridge across the line.

The line switch 0 and master switch D are of the general type disclosed in British Letters Patent No. 26,301 of 1906, and in the Western Electrician of Chicago, Illinois, of January 25, 1908. As here shown, the line switch C consists essentially of a plunger (not shown) attached to a plunger arm 38, and .a magnet 39. When the plunger arm 38 is attracted by the magnet 39 the plunger is forced into a bank of springs and s, forces the springs 40, 42, 44 and 46 into contact with-the springs 41, 43,45 and 47, respectively. The magnet 39 is composed of four windlngs, a pull-in winding 48, a cutoff winding 49, a line winding and an auxiliary winding 51. The magnetic circuit of the windings 48 and 49 is separate from that of thewindings 50 and 51. The pullin winding 48 is for the purpose of attracting the plunger arm 38 to force the plunger into the bank. The circuit of the winding. 48 is controlled by the calling subscriber through th'e medium of the line winding 50 and armature" 52. r The winding 51 prevents the armature ,52 from falling back immediately upon' the deenergization of the-wind ing 50. The-cut-ofi' winding 4!? is provided for the purpose of holding the plunger-ar n'1 38 in an o ierated position and for operating the cut-o armature 53. .If the winding 49 is energized while the armature 53 and plum J ger arm 38 arein an operated position,-both the armature and plunger arm will be held in this position after the winding 48 is deenergized; but if the winding 49 is energized while the armature 53 and plunger arm 38 are in'normal position, only the armature 53 will be operated, as the winding 49 is not as strong as winding 48. Although only one set of springs 40, 41, 4'2, 43

and 47 is shown, each line switch vided with a bank comprising a number of such sets of springs, each set forming the terminal of a trunk line'leading to a selector switch E. Each trunk is multipled through the corresponding bank contacts of a group of switches (l. The plungers normally rest (not shown) and through the medium thereterminal by the master switch D. The master switch -D consists essentially of a motor magnet 54 which operates the ratchet wheel 55, a bank of contacts com prising a number of individual, contacts a and one common segment 56, a busy trunk relay 57 and a locking relay 58. The wiper C is pro- 59 is adapted to always keep some one of the individual contacts a in electrical "connection with the common segment 56. By means of a suitable mechanical connection the rotary motion ofthe ratchet wheel 55 is transmitted tofthe plunger shaft to give said shaft a reciprocatin motion to' move the idle plungers back an forth'in front of the bank cpntacts- To the plunger shaft "there is also secured acam 50 having in its surface a number -.0f circular openings which are engaged by the pin 61 on the armature '62. The openings in the cam 60 l are so spaced that the pin ..61 can engage an opening only when the plungers that arein locking engagement with the plunger shaft are directly in front of a trunk. terminal.

7 The selector switchE is of the general iiilisclosedin United States Letters Pate en 1N1). 815,321, granted Mai-ch13,- 1906, to

Keith, Erickson and Erickson, but as here shown is adapted to operate in conjunction with a two-wire system a; a, a system in which there is'n'o ground at the substation. Among other details the. selector comprises a set of wipers 64, 65 and-63' carried upon a,-

shaft (not shown) which has a verticalmotion controlled by ,thevertical magnet 67 and a rotary, motion-controlled by the ro-' tary magnet; 68. f-Th'e usual' side-"switch,

comprising the wipersv 69,1695 '71'an'd'72 is "controlled b the private "magnt'w; operation 0 the switchis controlled by the the medium. of

calling subscriber throughv 7 TR 1 .ay ,0. re ease the double wound line 're magnet 74 is normally disconnected from the battery b the separationof springs 75 nd 76', whic are held out of engagement by the arm 77 as long as the switch shaft is in its lowest position. 'llhe relays 78, 79 no 7 I n v 7 1n locking engagement with a plunger shaft to the receiver at incl 86 ere relays that uecnergize slowly after their energizing circuits have been broken. The selector is provided with the so-callccl connector releese-i. 6., the mechanism restorecl immediately upon the energizetion of the release magnet rather than by its tlenergizetion, as shown in the said ctor patent.

. ..e repeater l? is adapted to receive i3 hpulses from the substation end to repeat them over the trunk conductors to at distant exchange. Among other details the re pester comprises a double-Wound line relay 81 which is similar to the relay 70 of the selector E. A slow-acting reley 82 is pro vioecl to open the circuit through the repeater While it is operating. The repeater is.

normally disconnected from the trunk, but is connected therewith by the relay as soon as e. selector switch engages the termi nails of that trunk. The impedance coil 8% is provided for the purpose of furnishing e across the line to prevent the switches the second exchange fr in. releasing. and yet forms a barrier to prevent the talking currents fIOHTPflSSlIlg from one sitle of the line to the other,

The connector I is of the general disclosed in Uniteil fitatcs Letters Patent #815,1F6, granted Merchw, 1906, to K ith, Eric :son and Erickson, and, like the tors. is inoclifierl to operate in e two-wire 11. general features of the connector are very similar to those of the solectm's the in in difference between tnei'o b" is provided no; in the circuits. The connector with e double-wound heelhritlgc relay 85 through which the callefl substation may he provided with talking buttery current. A. 1". .W'QI relay 86 is proi'i ierl for the QHFPOSS of connecting the. ringer generator L with the ceilecl line after connect. n has been completed. therewith.

in. or-ticr to give a clearer understanding my invention 1 will describe the complete operation of establishing a connection. between substations A and A. The number of the substation A will be assumed to he 220.

"ii hen the hook switch springs 30 anti .nie into engagement upon the removal l substation A, a circuit :loser through the line winding 50 of the r i or of i line switc. C. The circuit extends fromon '71 it" through springs 87 and 88, line 11 rluotoc substation springs 31 and 30, sprihgs Q8 and 2? primary whirling notion coil 24, transmitter 23, line 31*,

90 and 9, thence through the 2 incl- 'n 5D to battery lead iOO. The Winding u 303} energizing, ettrsctsthe armature which onerstes to close a circuit through pollen winding l8. This circuit extends from ground G" through springs 87 and 92, Winiings-e8 and 51.. contact point the erimiture to full back.

of the calling line. it the connector private bani; contact-s preof springs 88 and from rings 87 and 89 disconnects the ground G and winding from the line conductors 33 anal 3- The armature does not fell back immediately upon the tleener 'izstion of winding" 50, but remains held up for on instant by the currentfio'wing through Winding 51 in with Winding 48. ii hen the plunger arm 38 is attracted the magnet 39 it operates to force the plunger the bank and to force springs 9% end into engagement.

The engagement of springs and 95 short circuits the winding ,5 thus c: ising the said Winding to .iiecnergize sloui to allow When the armature 52 returns to normal position it breaks the circuit of the winding 48, allow-- ing it to deenergize, not, however, before the Winding 49 has been energized as follows: hen the bank springs 40 and 4:2 or forced into enge "emcn't with the springs 41 and E3, respectively, the line connection is extended to the selector causing its line relay 'Z() to become energized. The energizing circuit of relay extends from ground G through Winding .96. switch wiper 69. bank springs 43 and 42, thence over line 33 to and through substation A and back over line 34, through hank surings it and :1, side switch wiper aim ing 97 to battery lead. 100. 'The reie'y 'ZO,

upon energizii'ig, forces spring 98 into en-.,-

circuit extending from grouml G through relay springs 10:") and 10.6, h: nit springs sncl ist sncl winding); 4-9 of magnet to battery iced 100. This circuit is closed th ough the winding 49 before the Wind energized, and sew es to maintain the arms-- and plunger arm 38 in toperated po ions. the operation of role '78 =1 ground. potential is also extended. from ground G through tie bunk prings and ii end over the private norm-iii conductor 10? to the connector pirivete hunk contacts This grountl potential connectionby said connectors over the conductors 108 and 109.

' deenergizc. 3 5

When the bank springs 46 ands? are forced into engagement by the line switch plunger an energizing circuit is closed.

through the busy trunk relay 57. This circuit extends from ground G through bank springs 46 and 47, master switch bank contact 110 (which corresponds to the. trunk, seized), wiper 59, ,segment 56 and .relay 57. to battery lead 100. The relay 57, upon energizing, operates to close a circuit extending from ground Gr through the locking relay 58. The relay '58, upon energizing, withdraws the pin 61 from the opening in the cam 60 and closes an energizing circuit through the motor magnet 54. This circuit extends from ground G through magnet 54, interrupter springs 111,, contact point 112 and armature 62 to battery lead 100. Since this circuit includes the interrupter springs 111, the motor magnet 54 will continue to operate in a manner similar to that of a buzzer as long as the armature 62 engages contact point 112. The-continued operation of magnet 54 rotates the ratchet wheel 55 to move all idle plungers that'are in looking engagement with the plunger shaft away from the trunk just seized. When the plunger shaft has moved a short distance the wiper 59 passes oil of the contact 110. and allows the relays 57 and '58 to The armature 62 cannot fall back immediately 'upon the deenergization of relay 58, because the cam 60 has also been moved and the opening formerly engaged by'pin 61 has, been moved out of register therewith. The master switch will then continue to operate untilthe next opening passes under the pin 61, when the armature 62 will be allowed to drop back to open the circuit of magnet 5% and to lock the plunger shaft, with the idle plun ersstanding in front of the nex ttm'nk. I the first trunk after the one seized by the line switch 0 had been' busy, however, the wiper 59 would have found the corresponding contact grounded; consequently the relays 57 and 58 would have remained energized while the next opening was passing under pin 61 and the plungers would have been moved. past the busy trunk to an idle one. During the time the master switch 18 operating, the armature 62 is disengaged from the contact point 93 and springs 113 and 114 are allowed.t0

engage. By this arrangement the pull-in winding 18 of all switches which are controlled by the master .iwitch D are disconnected from battery to prevent the operation of any switch while its plunger'is in motion,

' call at thistime will receive the busiy .65

and any. subscriber attempting to make a signal. The busy signaling current passes rom the machine MQthrough the windings 51 and-4:8

magma v to ground G" if a subscriber attempts to I make a call when. the master switch is rotating. The current assingfthrough winding 51 produces an in need current in'wi nding gO which is connected with the line.

low immediately upon the removal. of the 'cciver at the calling substation and before "the callin deviceis operated-for the first digit. en the substation device is operated for'the first digit 2 t e bridge across. the line conductors 33' and Mfis opened twice b the 'se 'aration of im ulsc springs 27 an 28. e' opem'n o the bridge across theiline momenta the energizing circuit of the line re ay 70. ibi- 5 7o 'e'foregoingare the operations that folthe selector E. The relay 70, .upondenerf gizing, permits the spring relay 78 is slog actin it does not have time to eener uri t e momenta .o emng' of its cii di iit by 518 springs 101, The engagement of springs 98 and 99.9 .98 8 a circuit extending from ground KG through springs 98 and 99,103 an'd' lOfi, private magnet relay 79, vertical magnet 67 and si' e switch wiper 71 to battery lead 100. Since the digit called is 2 the vertical magnetroceives two impulses. over thiscircuit and; '1

operates to raise the shaft'wipers 64,65 and '60 two steps to a position opposite the second row or level 0 the energizin .circuit of the vertical magnet, is energized y the first impulse,and, being a slow-acting relay, remains energized until all the impu delivered. The relay 79, upon energizing, operates to. close a circuit extending from ground G through springs .115 and 116 and private magnet 7 3 to battery lead 100. \Vhen the relay 79ldeenergizes after the last impulse has been delivered to the vertical mag- 1 m e c spring 101 and engage spring 99. Since t e .l J' "1. V

7 bank contacts. Thepri vate magnet relay 79, which is included in see iorthe first digit have been net, this energizing circuit. through the private magnet 18 broken, allowing said magnet to deenergize to trip the side switch from first to second position. The movement of I of the first trunk of the second level,-to press iglown the armature of the private magnet 7 3, and to open the circuit of its own magnet at the interrupter springs 117.- When the rotary magnet circuit is thus opened its armature falls backand, if the first trunk i s.

already-in use, the private magnet armature the impedance coil 84 to prevent its interference with the operatioi of the switches at the other exchange.

When the substation calling device is erated for the second digit 2 the repeater operates in the manner explained to repeat two impulses over the conductors 130 and 131 to the selector The selector H o crates in the same manner as the selector to extend the connection over the trunk conductors 146' and 147 to the connector I. When the connection is thus extended to the connector the line relay 149 and release re-- lay 150 are energized and'operate to close a holding circuit through the release relay 151 of the selector H in the same manner that'the relays 81 and 125 of the repeater closed a holding circuit through the relay;

78 of the selector E. I

When the substation calling device is 0%: erated for the third digit 2 the repeater operates to repeat-two im ulsesto the line relay 149 of the connector 5 Each time the relay 149 deenergizes a circuit 'is closed extending from ground'G through springs 152 and 153,154 and 155, private magnet relay 156, vertical magnet 157 and side switch.-

wiper 158, to batterylead' 160. The vertical magnet receives two impulses over this circuit and operates to raise the shaft and wipers two steps; Therelay 156 is energized in series with the'verticalmagnet and 0 rates to close a circuit from ground G i as energize after the last impulse has been delivered to the vertical magnet, when the said relay operates to o n the circuitof the, 7 be private magnet thereupon Mnergizes and causes the side t 'ough springs 161 and 162 and private magnet 163 tobattery lead 160. The relay 156' is slow acting,.'like the relay 79 of the selector. E, and does not have time. 'to de private 163.-

. switch, to pass to second position. The move- I '1 ment of side switch wiper 158 from first to se ond position transfersthe battery con- 1111:435 n from'the vertical magnet 1517 to the 66 close the circuit of the private magnet 163 and to open it againaiter all the impulses are delivered. This operation of the private magnet causes'the side switch to pass to third positiornthu's extending the connection to the line #2220 upon whose terminals the. wipers 165 and 166 have been placed by the -.-statiou continuously,

guarding potentialis established at the conv nector private bank contacts of the called line, and an energizing circuit isclosed through the cut-off winding 169 of the line switch C. This circuit extends from ground side switch wiper 168, springs 170 and 1 1, private wi or 167, private bank contact 172 and cute winding 169 to battery lead 160., The Windingltii), upon ener-. 'ng, operates to disconnect the switch C om the lines of suhstation Aand to connect theline 173 with thecobauk contacts over thevnormal-conductor 175.

- when the side switch wiper 158 of the connector passes from the second to third posiaftien it dic0nnectsthebattery from the ro- ."tary 164 and closes a circuit throughthe ringerrelay'o86r This circuit extends from ground GP v through the interrupter 17,6, springs'17-7 and 178, relay 86 and side a svn'tclr wiper15 8'to battery lead 1,60, The

relay 86,;. upon energizing, operates to disconnectthe callmgand called lines and to bridge'the ringer generator Lacross the calledline: Since thecircuit of the ringer relay SG-includer' the interrupter 176, the

said relay is energized only; intermittently 9 soasnottormgthehel ls atlthe called sub- When the called removes his -reeeiver from the switch hook, or as soon thereafter as the ringer relay 86 deenergizes, if it happens to he energized at the time, the called substation is provided with talking current. The path over which this talking current flows extends from ground G" through winding 179 of the back-bridge relay 85, ringer relay springs 180 and 181,- side Switch wiper 182, shaft wiper 166, lino 174, springs 183 and 184 (which are closed by the removal of the receiver from the hook), thence through the substation impulse springs, primary winding of the induction coil, transmitter, andback over conductors 173 and 175', wiper lfifiyiside switch wiper 185, relay-springs 186 and 187 and winding 188 of relay 85," -the battery lead 160,- Since both windingsof relay 85 are included in the circuit just traced, the said relay energizes, and by separating the springs 177 and 178 prevents the further energi'zation of the ringer relay 86. The two'subscribers may now carry on an uninterrupted conversation over the heavy conductors shown in the drawings. v

After a conversation is completed the son tral ofiice apparatus is released by the return of the receiver to the switch hook at the calling substation. When the receiver at the substation A is replaced upon the. switch relay 81 of the regxeater F. The relay 81, upon cleenergizmg, opens the briclge across relay (lecnergizes after a short time anal.

opens the circuits of the cutclli relay 83 can of the release relay T8 of ice selector E engl cuts the ground from the conductor 129 leading t cut-oli'iwin limg' of the line 0 i switch Wlloll belongs to the trunk conduc- J- tors ancl; 131. When the release relay 7'8 of the selector E dcner izes it breaksthe holding circuit oftlie winding 49 of the line switch C closes an energizing circuit through the release magnet 7% or the Selector E, The Lleenergisction of the Wincling 49 allows the plunger the line switch {3 to he rest-creel to normal "position, thus ilisccnmeeting the lines and 34 from the selector E. The circuit which is clcsed throngs the release magnet 74 of the selector by the cleenergizetion of relay 78 extends from ground G through. springs 98 and 99, 103 and 102, megneo'il and oil-normal springs 76 and '75 to battery leecl 100. The magnet 7%, upon energizing, operates to immeiately release the mechanism or" the selector to allow it to be restored to normal position. As soon as the switch shaft reaches its lowest position the springsl and 76 are separated to disconnectthe battery from the magnet 7% to ellow'it to clecnergize.

The opening or the bridge across the trunk lines 130 and 131 by the ile'cnergization of the repeater relay 81 allows the line relay 149 of the connector I to clenergisc to destroythe holrliii circuits oi the release relefis 1'50 and 153. or the switches I and H, respectivcly. The relays 150 and 151, upon (leenergizing, complete the energizing circuits of the release magnets-18 an 199 Of 5119i? respective switches in the some manner as QXpla'llnfiCl fOl' the selector F. The relay E51, upon (ldnergiZing, also breaks the energizihg circuit of the holding winding of the switch C and removes the guarding poten tisl from the conductor 1-10, which leads to the private bank contacts the selector,

sis

closure of this circuit, and, by forcing the spring 195 into engagement with the spring .196, closes it looking circuit through the private meg-net 163 independent of the relay 15*. This locking circuit extends from the grounded bank contact to the contact point 193, as before traced, and thence through the springs ancl 195 and through the mag net 163 to the battery lead When the private magnet relay 156. denergizes, with the pri'vete'inegnct thus locked, the side switchremeins in second position and a circuit is closed extending from ground G through the springs 161 and 197, B8 and. 199 en relay 200 to the battery lead 160. Therelay 200, upon energizing, disconnects the rotary magnet 16% from the impulse spring 153 and shifts the holding ground of relay 85 and magnet 163 from the private bank contact to ground G to lorevent the completion oil the connection in the guarding ground should be removed. As long eds-the side switch thus remains locked in second position the calling subscriber reccivesjc busy signal over a circuit exteniling from the battery lead 160 through the hos machine lil, private magnet SPl'lilPS and 202, contact point 203, side switch wiper 182,1'll'1g6f relay springs 181 and 180, conclenser 20 i, thence over the heavy conductors shown in. Figs. 2 and 1 to and through suostetion 131-. and back over the other side of the line, thence through the upper Winding of the connector line relay 1&9 to the starting: point. Theswitchesorc released from this position the hanging up of the receiver at the calling substation in practically the switches which have access to the tr'unl, /ssme inglnner as when a complete connec- 0V8? he conductors 191 and 192. The gle encigizction of the cut oil Winding of the S'lllCll all the sail switch to be resto ed to normal position incl all the eppci'ctus e11 loyecl in the ccnnec ion is ready for another call.

The f=3i&f"0l?l is an explanation of the manner in which connection is completed with an idle line. it will now be explained] how the cellingsuhscriber'is given the busy -signsl in case the line called is slreacly in .use.

It has been seen that Whenever a lineis busy, eitliei by'recson of having made 's call or by having been called, there is present gunrcling ground potential upon the corresigonoicg pum ce heel; contscs-n -the tion is established.

lVhen the trunk lines 130 and 131 are usecl to extend accnnection in the opposite clirectiozi the operation is identical with that above explainerl, except that the repeater the right-hand end of the trunk and the line switch at the left-hand end are used in: stead of the repeater l1 and line switch C ltis always the repeater that is situatecl in the exchange in which the call originates that is use-fl. 1

From the foregoing it will be seen that I provicle e trunk line'hoving a nonhuniericcl trunking switch at each enil thereof; that eu-cliswitch is controllecl by a repeater.

i l frefiersbljvtheserepeeters are sllotterlto the trunk line and located at opposite ends- 1 thereof. In this way the repeater atoneend. of the trunk line. may-he controlled to oper-- ate the non-numerical trunking switch. at the other end'of s'aid- In a similar mannor the other repeater and. non-numerical a. trunking switch ma be controlled to extend 3 a connection-over t e trunk line'in thexoiposite direction -The arrangement issue 10' as explained," that the operation of the repeater at one end of the trunk-linedoesnot distunb the normal condition of the trunking switch at the same end-of the trunk line,

Y but simply controls the switch at theother end thereof. When thetrunk line is seized at one end it is then automatically made busy at both ends thereof, so that any other calling subscriber must then use some other trunk. The repeaters, it. wilhbe seen, 0011- trol the operation of the non-numerical trunking switches for extending calls, and also control the release of the connection after the subscribers are through talking.

What I claim as my invention is: r

-1. In a telephone system, a two-way trunk line, a nonmnmerical trunking switch for each end of said line, a repeater at one end of saidtrunk line adapted to control the 7 switch at the other end thereof, and trunks, each switchadapted to automatically select, idle trunks. q

2. In a telephone system, a two-way trunk line,- anon-numerical trunking switch for each end bf said line, a repeater at one end of said trunk line'adapted to control the switch at the other end thereof, instrumentalitie's operative to make either end of the line busy when the other end is seized, and

trunks, each switch adapted to-automatically select idle trunks.

3. In a telephone system, a two-way trunk line, a non-numerical trunking switch for each end of said line, a repeater at one end a of said trunk line adapted to control the switch at theother end thereof, each switchadapted to automatically extend a connection from said line in the direction of the called subscriber, numerical trunking switches for seizing either end of said trunk 1ine,,and instrumentalities operative to render either end of said trunk line busy when i the other end is seized. 1 I

4. In a telephone system, a two'way trunk line, a non-numerical trunk'ng switch for each end ofmid line, a repeater at one end of said trunk line adapted to cohtrol the switch at the other end thereof, instrumentalities operative to make both ends of said trunk line busy when either end thereof is seized, .andtrunhs, each switch adapted to automatically select idle trunks.

5. In a't elephone system, a two-way trunk line, a non-numerical trunking switch for each end of said line, a repeater at one'end of said trunk line adapted tocontrol the trunks, a set; of non-numerical t said switches over line, 5 switches, for .'auton1a.hcal1y,-;

- line circuits.

' the said trunk attlie other end thereo'f,each switch adap ed-16o automatically extend a trunking connection from'said line 'in the direction of called suhscriber, numerical trunking switches for seizing either end of said trunk line, and instrumentalities operative to renderv both ends ofsaid trunk line bu either end thereof is seized.

6.;'In a telephone system, a set 0 sy when f two-way switchesL-for the said trunks at one end thereof, a master switch for said set of trunking switches, repeaters for the said I v trunks adaptied to control said switches, another setof non-numerical switches for said 30, trunks at the other end thereof, and another master switch for said last-mentioned set of switches 7- ln at l ph ne y 'm, trunkline, e

switch for, automatica1l one the other, meansincluding arepeater for said switch oYer a complete metallic line circuit, and automatic 8. In a telephone-isystem,"a,trunk l-ine,'an .automapic witchjorseizing of and line, anonumerjforangomatic n c n t me trunk-line, the first l ne fl'ff repeater vfor. controlling said switch, means'for vely ing the other end of said s emmed 9, nat lep n sy m, str w: v

nn t f m here f a of the u h o i i g easnd o and means including repeaters for trolling said switches oyefr 10. In a telephone trunk automatic switches for extending connection from either end thereof in the direction of, the called subscriben'repeatere- 11s for said-trunk adapted to control said switches, other automatic switchcsfor ing either end of said trunk line, and means. by which all of said switches are mntr olled over complete metallic line circuits.

11. Ina telephone system, a trunk-line, a. first selector-operative in acco ncewith the first digit of the called number to seize one end of said trunk-line, a second selector operative in accordance with the digit of the called number to extend the connection in the direction of thecal-led subscribcr, a non-numerical trunki pg switch .for automatically ext-en ding connection from.

line to the second selector,

line, a non-numerical tr nk ng 86 ri s-45 i mi itate metallic ;line n clrwits, means ifi t mati allyi-m i' and means including repeaters whereby said switch and second selector are controlled oi'er complete metallic line circuits.

12. In a telephone system, a two-way trunk, an automatic switch for including said trunk in a calling connection in one direction, another automatic switch for in-. cluding said trunk in a calling connection in the other direction, an. automatic switch controllable over the two. sides of the trunk line in series for completing the call in one direction, another automatic switch controllable over the two sides of the trunk line in series for completing the call in the other a direction, and a repeater for one endof said trunk. 13. In a telephone system, av two-way trunk line, an automatic switch for extending connection from one end of said trunk.

line, another automatic switch for extending connection from the other end of said trunk line, each switch controllable over the two sides of the trunk line in series, and a repeater for one end of said trunk.

14. In a telephone system, a twoway trunk line, a non-numerical trunking switch for each end of said line, a repeater for each end of said trunk line, each repeater adapted'to control the switch at the other end of the trunkline, and trunks, each switch adapted to automatically select idle trunks.

15. In a telephone system, a two-way trunk line, a non-numerical trunking switch for each end of said line, a repeater for each 3 end of said trunk line, each repeater adapted to control the switch at the other end of the trunk line, instrumentalities operative to make either end of the line busy when the other end is seized, and trunks, each switch 40 adapted to automatically select idle trunks. 16. In a telephone system a twoeway trunk line, a non-numerical trunking switch for each end of said line, a repeater for each end of said trunk line, each repeater adapted to control the switch at the other end of the trunk li each switchadap'ted to automatically extend a trunking connection from said line in the direction of the called subscriber, numerical trunking switches for seizing either end of said trunk line, andinstrumentalities operative to render either end of said trunk line busy when the other end is'seized. I

17. In a telephone system, a two-way trunk line, a non-numerical trunking switch" 1 for each end of said line, a repeater for each end of said trunkline, each repeater adapted to control the switch at the other end of the trunk line, instrumentalities operatit e to make both ends of said .trurik line busy when either end thereof is seized, and trunks, each switch adapted to automatically select idle trunks. v ,18. In a. telephone system, a twd-way trunk line, a non-numerical trunking switch trunk line,

ing switches for the said trunks at one end thereof, a master switch for said set of 30 trunking switches, another setof nonnumerical switches for said truuks', at the other end thereof, another master switch for said last-mentioned set of trunking switches, and a repeater for each end of each 35 trunk adapted to control said switches.

20. In a telephone system, a two-way switches for automatically extending connection from either end thereof in the direction of the called subscriber, automatic switches for seizing either end of said trunk line, and means comprising repeaters for controllingall of saidfirstmentioned switches over complete metallic line circuits.

21. In a telephone system, a two-way, trunk line, automatic switches for extending connection from either end thereof in the direction of the called subscriber,other automatic switches for seizing either end of said trunk line, and means by which all of said switches are controlled over complete metallic line circuits, including repeaters for the opposite end of said trunk line.

22. In a telephone system, a two-way trunk, an automatic switch for including said trunk in a calling connection in one direction, another automatic switch for including said trunk in a calling connection, in the other direction, an automatic switch 110 controllable over the two sides of the trunk line in series for completing the call in one direction, another automatic switch controllable over the two sides of the trunk line in series for completing the .call in the other direction, and a repeater for each end of said trunk. a v

23. In a telephone system, a two-way trunkline, an automatic switch for extending connection from, one end of said trunk line, another automatic switch for extending connection from the other end of said trunk line, each switch controllable over the two sides of the tr i line in series, 'anda re peater for each Iefidof said trunk.

24. In a telephone system, a trunk line, a repeater at each end of said trunk line, a

' nonnumerical sw tcher each and er sue line, meanswfor controllingpeater t'o operate the at the oth of the trunk line, and means for controlling the other repeater to operate the other switch.

25. In a telephone system, a trunk line, a

trunk line, and means for controlling the other repeater to operate the other switch,

each repeater being controlled by a metallie line circuit.

26. In a telephone system, a trunk line, a repeater at each end of said trunk line, a non-nun'zerical switch at each end of said trunk line, means for controlling one repester to operate the switch at the other end of the trunk line, and means for controlling the other repeater to operate the other switch, each repeater having means for controlling the two sides of the trunk line 1n 27. In a telephone system, a trunk line, a

' non-numerical switch associated with each end said trunk line for extending connection from said trunk line, other automatic switches for extending, a connection to said trunk line, a repeater for one end of said trunk line adapted to repeat impulses over said trunk, a cut-off relay for said nonnumerical switches, and means for energizing the cut-01f relay of the non-numerical switch associated with the end of the trunk seized when said automatic switches seize one end of said trunk.

28. In a telephone system, a trunk line, means for seizing one end of said trunk line, a repeater and a non-numerical switch associated with each end of said trunk, a cut-off relay for each of said non-numerical switches, and. means for energizing one of said relays when said trunk is seized.

29. In a telephone system, a trunk line, a

non-numerical switch associated with eachend of said trunk line for extending connecswitches, and means for energizing the cutrelay of the non-numerical switch'assoelated wlth the end of the trunk seized when said automatic-switches seize one end of said trunk.

30.,In a telephone system, a trunk line, means controllable over a metallic circuit for seizing one end of said trunk line, a

repeater and a non-numerical switch assomated with each end of said trunk, a cutofi relay for each of said non-numerical of, a pair of condensers in said trunk line,

from said trunk linewhen said repeater is operating.

32. In a telephone system, a two-Waytrunk line, a non-numerical switch at either end of said trunk line for selecting idle trunks extending therefrom, a repeater at one end of said trunk line controlling the non-numerical switch at the other end thereof, a pair of condensers in said trunk llne,

and a slowacting relay adapted to be energized when said repeater is operating to disconnect said condensers from said trunk line. 33. Ina telephone system, a two-way trunk and means for disconnecting said condensers line, a non-numerical switch at either end i of 'said trunk line for selecting idle trunks? eirtendingtherefrom,'a repeater at one end of said trunk lin'e controlling, over a metallic circuit, the non-numerical switch at the other end thereof, a pair: of condensers in said trunk line, and means for disconnect-- ing'said condensers from, said trunk line when said repeater is operating.

34. In a 'telephone'-system, a two-way trunk line, a non-numerical switch at either end of said trunk line for selectingidle trunks extending therefrom, a repeater at one end of said trunk line controlling, over a metallic circuit, the non-numerical switch at the other end thereof, a pair of condenser-s in said trunk line,'and a slow-acting relay adapted to be energized when said repeater is operating to disconnect said condensers from said trunk line. I

35. In a telephone system, a trunk line, a repeater and an automatic non-numerical line switch connected to one end of said trunk, and a repeater and a non-numerical line'switchconnected to the opposite end of said. trunk.

36. In a telephone system, a two-way trunk line, an automatic line switch. at each end of said trunk for'extending connection from said end, and a repeater at each end of said trunk.

Signed by me at Chicago, Cook'county, Illinois, this 29th day of March, 1910. i

' TALBOT G. MARTIN.

Witnesses:

EDWARD D. FALES, ARTHUR J. RAY. 

